Fig. 1. Relational diagram of lidar transmitter and receiver

Fig. 2. Paraxial point imaging in a telescope

Fig. 3. The relationship between the spot on the focal plane and the field stop

Fig. 4. Cross-section of the laser beam in the field of view

Fig. 5. The theoretically calculated geometric factor profiles

Fig. 6. Geometric factor profiles of different laser beams

Fig. 7. Geometric factors of a certain laser beam under different beam expansion magnifications